MARINELLI ET AL.
1365
2
5
+
+
5
4% yield) as a colorless oil: [α]
= +4.0 (c = 0.6 in
CH CH ); HRMS (ESI , m/z): [M + H] calcd for
2 3
D
1
+
CHCl ); H-NMR (400 MHz, CHCl , δ): 6.76 (s, 1H, Ar
C H NaO S , 361.1271; found: 361.1270.
3
3
18 26
2 2
4
1
1
0
-H), 3.85 (dd, 1H, CH O), 3.77 (dd, 1H, CH O),
α β
.90–1.76 (m, 1H, CHCH ), 1.60–1.48 (m, 1H, CH CH ),
3
α
3
.32–1.18 (m, 1H, CH CH ), 1.01 (d, 3H, CH CH), and
2.3.8 | Oligo{3-[(S)-(2-methylbutyl)
sulfanyl]thiophene} (PTSR*)
β
3
3
+
+
.94 (t, 3H, CH CH ); HRMS (ESI , m/z): [M + H] calcd
3
+
2
for C H Br OS , 326.9053; found: 326.9052.
9
13
2
To a three-necked flask containing TSR*Br (0.313 g,
2
0.9 mmol), dried 2-methyltetrahydrofuran (5 ml) and 2 M
2
.3.6 | 2-Bromo-3-[(S)-2-methylbutoxy]
of hexylmagnesium bromide in Et O (0.5 ml, 1.0 mmol)
were sequentially added under stirring and nitrogen
atmosphere. The solution was heated to reflux in the
2
thiophene (TOR*Br)
The same procedure described for TSR*Br was followed
starting from TOR* (0.565 g, 3.3 mmol) and NBS
dark for 1 h. Then, Ni(dppp)Cl (0.024 g, 5 mol%) was
2
added, and the mixture left under stirring and reflux
overnight. After being dried, chloroform was added, and
the mixture was washed with water, followed by drying
over Na SO . The organic phase was concentrated to
(
9
0.591 g, 3.3 mmol) in DMF obtaining TOR*Br (0.740 g,
0% yield) as a light brown oil: H-NMR (400 MHz,
1
CHCl , δ): 7.18 (d, J = 5.9 Hz, 1H, Ar 5-H), 6.73 (d,
3
2
4
J = 5.9 Hz, 1H, Ar 4-H), 3.89 (dd, 1H, CH O), 3.81 (dd,
small volume and finally treated with hot MeOH to
afford PTSR* (0.121 g, 73% yield) as a dark red solid; H-
α
1
1
H, CH O), 1.88–1.78 (m, 1H, CHCH ), 1.62–1.50 (m, 1H,
β
3
CH CH ), 1.32–1.20 (m, 1H, CH CH ), 1.01 (d, 3H,
CH CH), and 0.95 (t, 3H, CH CH ); HRMS (ESI , m/z):
NMR (400 MHz, CHCl , δ): 7.38 (s, 1H, backbone Ar
α
3
β
3
3
+
4-H), 3.00–2.60 (m, 2H, CH S), 1.80–1.15 (m, 3H, CH CH
3
3
2
2
3
+
+
[
M + H] calcd for C H BrOS , 248.9948; found:
and CH CH ), 1.10–0.95 (m, 3H, CH CH), and 0.95–0.78
9
14
3
2
3
2
48.9947.
(t, 3H, CH CH ).
3 2
0
2
2
.3.7 | (+)-3,3 -Bis[(S)-(2-methylbutoxy)]-
2.3.9 | Oligo{3-[(S)-(2-methylbutoxy)]
thiophene} (PTOR*)
0
,2 -bithiophene (T2OR*)
A solution of n-butyl lithium in hexane 2.5 M (0.4 ml,
To a three-necked flask containing TOR*Br (0.296 g,
2
1
.0 mmol) was added dropwise under inert atmosphere
0.9 mmol), dry THF (5 ml) and 2 M of hexylmagnesium
ꢁ
at −70 C to a solution of TOR*Br (0.215 g, 0.9 mmol) in
bromide in Et O (0.5 ml, 1.0 mmol) were sequentially
2
dry THF (3 ml). After 30 min, Fe(acac) (Alfa Aesar)
added under stirring and nitrogen atmosphere. The solu-
tion was heated to reflux in the dark for 1 h. Then,
3
(0.494 g, 1.4 mmol) was added to the reaction mixture,
and the mixture allowed to reach room temperature
under stirring overnight before quenching with water.
Ni(dppp)Cl (0.024 g, 5 mol%) was added, and the mix-
2
ture was left under stirring and reflux for 1 h. After being
dried, chloroform was added, and the mixture was
washed with water, followed by drying over Na SO . The
The aqueous phase was extracted with Et O, and the
2
combined organic phases were washed with brine. After
2
4
being dried over Na SO4 and removal of the solvent
organic phase was concentrated to small volume and
2
under reduced pressure, the crude product was purified
by column chromatography on silica with hexane as elu-
ent to afford T2OR* (0.050 g, 16% yield) as a dark green
oil constituted by a 60:40 mixture of HH and HT
finally treated with hot MeOH to afford PTOR* (0.079 g,
53% yield) as a dark blue powder: H-NMR (400 MHz,
1
CHCl , δ): 7.02–6.80 (bm, 1H, backbone Ar 4-H),
3
4.10–3.90 (m, 2H, CH O), 2.08–1.90 (m, 1H, CH CH),
2
3
25
1
regioisomers: [α]D = +42.7 (c = 0.4 in CHCl ); H-NMR
and 1.78–0.86 (m, 8H, CH CH, CH CH and CH CH ).
3
3
3
2
3
2
(
5
400 MHz, CHCl , δ): 7.07 (d, J = 5.7 Hz, 2H, Ar 5-H and
3
0
-H, HH), 7.02 (d, J = 5.7 Hz, 1H, Ar 5-H, HT), 6.88 (d,
0
0
J = 1.8 Hz, 1H, Ar 3 -H, HT), 6.83 (d, J = 5.7 Hz, 2H, Ar
2.3.10 | Oligo{3,3 -bis[(S)-(2-methylbutyl)
0
0
4
6
4
2
-H and 4 -H, HH), 6.81 (d, J = 5.7 Hz, 1H, Ar 4-H, HT),
sulfanyl]-2,2 -bithiophene} (PT2SR*)
0
.10 (d, J = 1.8 Hz, 1H, Ar 5 -H, HT), 4.01 and 3.94 (m,
0
H, 3- and 3 -OCH and 3-OCH , HH), 4.01 and 3.94 (m,
To a solution of T2SR* (0.075 g, 0.2 mmol) in anhydrous
α
β
0
H, 3-OCH and 3-OCH , HT), 3.81 and 3.73 (m, 2H, 4 -
CHCl (8.1 ml), FeCl (0.131 g, 0.8 mmol) was added
α
β
3
3
0
OCH and 4 -OCH , HT), 2.00–1.80 (m, 4H, CHCH ),
1
1
under a weak stream of nitrogen at room temperature.
The suspension was left under stirring for 24 h, turning
from greenish to dark blue color. Then, 50 ml of THF
α
β
3
.70–1.50 (m, 4H, CH CH ), 1.44–1.18 (m, 4H, CH CH ),
α
3
β
3
.12–1.06 (m, 12H, CHCH3), 1.02–0.90 (m, 12H,